Spinal fixation system having locking and unlocking devices for use with a multi-planar, taper lock screw

ABSTRACT

Provided is a spinal fixation system including a taper lock screw including an inner housing and an outer housing that are translatable relative to one another to transition the taper lock screw between a locked position and an unlocked position. A locking device releasably connects to and operationally interacts with a flange of the taper lock screw. An unlocking device releasably connects to and operationally interacts with inner housing unlocking tool receptors of the taper lock screw to unlock the taper lock screw.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/182,902, filed on Jul. 14, 2011, which claims priority to, and thebenefit of, U.S. patent application Ser. No. 11/493,624, filed on Jul.27, 2006, which claims priority to, and the benefit of U.S. ProvisionalPatent Application Ser. No. 60/721,482 filed on Sep. 29, 2005. Thedisclosures of these prior applications are hereby incorporated hereinby reference in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to orthopedic surgery, and in particularto devices for stabilizing and fixing the bones and joints of the body.Particularly, the present invention relates to a spinal fixation systemthat includes surgical instruments that can be used for locking orunlocking a taper lock screw, the screw preferably being multi-planarand useful for securing a spinal rod or plate to a vertebra.

2. Background of Related Art

The spinal column is a complex system of bones and connective tissuesthat provides support for the human body and protection for the spinalcord and nerves. The adult spine is comprised of 24 vertebral bodies,which are subdivided into three areas including seven cervicalvertebrae, 12 thoracic vertebrae and five lumbar vertebrae. Between eachvertebral body is an intervertebral disc that cushions and dampens thevarious translational and rotational forces exerted on the spinalcolumn.

There are various disorders, diseases and types of injury which thespinal column may experience in a lifetime. The problems may include butare not limited to scoliosis, kyphosis, excessive lordosis,spondylolisthesis, slipped or ruptured discs, degenerative disc disease,vertebral body fracture, and tumors. Persons suffering from any of theabove conditions typically experience extreme or debilitating pain andoften times diminished nerve function.

One of the more common solutions to any of the above mentionedconditions involves a surgical procedure known as spinal fusion. Aspinal fusion procedure involves fusing two or more vertebral bodies inorder to eliminate motion at the intervertebral disc or joint. Toachieve this, natural or artificial bone, along with a spacing device,replaces part or all of the intervertebral disc to form a rigid columnof bone and mechanical hardware. In this way damaged or diseasedvertebrae are connected to healthy adjacent vertebrae to stabilize thespine while the bone grows and fusion takes place.

The mechanical hardware used to immobilize the spinal column typicallyinvolves a series of bone screws and metal rods or plates. When thespine surgery is posteriorly performed, it is common practice to placebone screws into the vertebral bodies and then connect a metal rodbetween the bone screws thus creating a rigid structure between adjacentvertebral bodies. When the spine surgery is performed anteriorly, it iscommon practice to attach a thin metal plate directly to the vertebralbodies and secure it to each vertebral level using one or more bonescrews.

Many conventional devices for locking a spinal rod to a fixation hook orscrew do not offer the needed variability to allow the spinal rod to beeasily connected to adjacent vertebrae, which are not aligned on thesame plane. In some cases the use of these devices may be permanentlyimplanted in the subject. In other cases, the devices may be implantedonly as a temporary means of stabilizing or fixing the bones or bonefragments, with subsequent removal when no longer needed. It is alsocommon that device implants that were intended to be permanent mayrequire subsequent procedures or revisions as the dynamics of thesubject's condition warrant. For these reasons, it is desirable that animplanted device be provided, which can be easily locked and unlocked asdesired by the surgeon.

In recent years some effort has been made to provide taper lock bonescrews and further to provide taper lock bone screws that aremulti-planar; however, even when multi-planar type bone screws have beendeveloped, the use of those screws has proven difficult because thelocking and unlocking instruments that are used by the surgeon duringthe surgical procedure are of a generic design and inadequate to quicklylock or unlock the bone screws. In addition, with prior conventionalscrews the mode of locking the screw and rod typically involves setscrews or nuts, the application and tightening of which generatestwisting or torsional forces, i.e., torque, which are transmittedthrough the screw to the bone to which the screw has been inserted. Suchtorsional forces can alter the disposition of the screw in the bone orcan damage the bone, which may be of poor strength or quality inpatients undergoing surgery. As such, the torsional forces can adverselyaffect the outcome of the procedure.

To meet the problem of securely connecting adjacent vertebrae, not on acommon plane, a requirement exists to provide a multi-planar, taper lockscrew that can be easily inserted and easily removed from the vertebralbone as desired and to provide the specialized instrumentation that canfacilitate quick locking and unlocking of such a screw. It is alsodesirable that such a screw and the instrumentation for locking andunlocking the screw be configured so that the screw can be locked intoposition in relation to the bone and the spinal rod without the need toexert any additional torque to the screw. Additionally, the developmentof such a multi-planar screw and the locking and unlockinginstrumentation can be designed so as to eliminate the need for anadditional locking piece, such as the conventional, often difficult tomanipulate set screw or nut that is a small separate element from thebone screw and normally requires threading with the application oftorque onto the screw.

Conventional efforts to meet this need have fallen short in that nosystematic approach has been provided that adapts the spinal rod to themulti-planar environment of the spine by using a multi-planar lockingbone screw with specifically designed locking and unlocking instrumentsthat present a quick, torqueless method of locking and unlocking the rodto the screw. Thus, while much attention is generally given todeveloping improved implants, the benefits of the innovations are oftennot fully realized because the appropriate instrumentation is notdeveloped in a parallel systemic fashion.

For this reason, a major challenge of spine surgery is in thedevelopment of surgical instruments or instrumentation, for the surgeonto use during the implantation of the mechanical fixating structure. Theinstrumentation must be easy to use, effective, durable and mostimportantly, must not interfere with or cause further damage to thepatient's anatomy.

While surgical instrumentation can sometimes be generic and effectivelyused in a variety of procedures, it is becoming more prevalent that theinstrumentation is designed to be part of a specific system orprocedure; that is, the instrumentation is designed to work best withcertain implants.

Often implants are difficult to access and grasp with instruments thusincreasing the surgeon's workload and prolonging the amount of time thatthe patient is in surgery. As improvements are made in the spinalimplants themselves, it is often found that existing or genericinstruments are inadequate to the task of effectively and efficientlymanipulating the spinal implant. This is particularly troublesome whenattempting to reduce a spinal rod into a receiving portion of an implantsuch as a pedicle screw or attempting to later release the spinal rodfrom that screw.

For these reasons there remains a need for a device which, in one simpleaction such as squeezing a lever, can reduce a posteriorly introducedrod into a pedicle screw and securely lock the rod into the pediclescrew. Conversely, there remains a need for a similar device which,through an equally simple action, can unlock a pedicle screw therebyreleasing the posteriorly introduced rod.

SUMMARY

The present system provides novel component devices and a method forselectively locking and unlocking a spinal rod to a bone screw usingeasily operated, torqueless locking and unlocking devices or instrumentsthat are specifically designed for use with a novel taper lock screw.

Also provided is a system that includes several devices including anovel taper lock screw, which is preferably a multi-planar taper lockscrew, a torqueless, easily operated locking instrument, and atorqueless, easily operated unlocking instrument.

Also provided is a multi-planar taper lock screw that is configured tobe releasably connected to a spinal rod at the uppermost portion of thescrew and physically connected to a first vertebra using the lowerthreaded portion of the screw. The multi-planar aspect of the screwenables it to be used to make such a connection to a rod that can alsobe connected to an adjacent vertebra not in the same plane as the firstvertebra. The multi-planar taper lock screw has a novel configurationthat includes a proximally located easily accessed flange. That proximalflange with other specifically designed structural elements of the screwis configured to facilitate grasping of the screw by a locking and/orunlocking instrument that can insert and lock a spinal rod securely intoplace in the screw or selectively unlock the rod from the screw usingcomplementary designed unlocking instruments.

Also provided is a locking instrument that includes complementaryconfigured operational features to that of the multi-planar taper lockscrew. The locking instrument is designed to facilitate the insertingand torqueless locking of a rod, such as a spinal rod, into aselectively locked/unlocked connecting rod slot on the uppermost portionof the multi-planar taper lock screw.

Also provided is an unlocking instrument that is configured withcomplementary features to that of the multi-planar taper lock screw. Theunlocking instrument is designed to facilitate the torqueless unlockingand release of a rod, such as a spinal rod, from a selectivelylocked/unlocked connecting rod slot on the upper most portion of themulti-planar taper lock screw.

Also provided is a system that includes a novel multi-planar taper lockscrew configured to have a slidable outer housing over an inner housingcontaining a spherically configured screw head about which anarticulating recess of the inner housing articulates and a connectingrod slot of the inner housing within which a removable spinal rod can bemanipulated; the outer housing being capable of being selectivelypositioned relative to the inner housing so as to fully lock the screwhead and the spinal rod in position within the inner housing. The systemalso includes specifically designed locking and unlocking devices orinstruments.

Also provided is a system that includes a novel multi-planar taper lockscrew configured to have a slidable outer housing over an inner housingcontaining a spherically configured screw head around which the innerhousing can pivot and a removable spinal rod wherein the outer housingcan be selectively positioned to fully lock the screw head and thespinal rod in position within the inner housing or can be selectivelypositioned to lock only the screw head in position while permitting asliding and rotating motion of the spinal rod about its long axis withinthe inner housing.

Also provided is a kit that can include at least two of the novelmulti-planar taper lock screws, at least one rod device, and the novel,complementary configured locking and unlocking instruments.

Also provided is a method of using the novel system to fixate a portionof a spinal column using one or more multi-planar taper lock screws andselectively using the complimentarily configured locking or unlockingdevices, wherein the surgical procedure employed, in comparison toconventional methods, is quickly accomplished for locking or unlockingof the rod from the screw without applying additional torque to thescrew.

These and other embodiments of the present disclosure will be describedin detail below with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure are described herein withreference to the accompanying drawings, wherein:

FIG. 1 shows a perspective view of a surgical rod positioned within theconnecting rod slot of each of three multi-planar taper lock screws, thescrews being in an unlocked mode;

FIGS. 2A, 2B, 2C, and 2D show components of the system including across-sectional view of the multi-planar taper lock screw (FIG. 2Aunlocked and FIG. 2B locked with a spinal rod in place), a lockingdevice (FIG. 2C) and an unlocking device (FIG. 2D), each of the lockingand unlocking devices being specifically and distinctly configured foruse with the multi-planar taper lock screw so as to selectively lock orunlock a spinal rod therefrom;

FIG. 3A shows a side view of the screw component of the system, thescrew being configured in a locked or closed position, that is with thesurgical rod locked in place within the inner housing of the screw;

FIG. 3B shows a side view of the screw component of the system, thescrew being configured in an unlocked or open position, that is with asurgical rod in place within the screw but not locked and securedtherein;

FIG. 4A shows a cross-sectional view of the body portion of the screwcomponent of the system in a closed position, that is with a surgicalrod secured and locked in the screw body;

FIG. 4B shows a cross-sectional view of the body portion of the screwcomponent of the system in an open position, that is with a surgical rodin place within the screw body but not locked and secured thereto;

FIG. 5 shows a side view of a bone screw locking device component of thesystem;

FIG. 6 shows an isometric view of a bone screw locking device componentof the system;

FIG. 7A shows a front view of a bone screw locking device component ofthe system with the locking device component configured to be moved intoan operational connection with the screw component;

FIG. 7B is a cross-sectional view along section line A-A of FIG. 7Ashowing the locking device component of the system with the lockingdevice component configured to be moved into an operational connectionwith the screw component;

FIG. 8 shows a cross-sectional view of the lower portion of the bonescrew locking device component operationally engaged with the screwcomponent in a locked configuration;

FIG. 9 shows a side view of a bone screw unlocking device component ofthe system;

FIG. 10 shows an isometric view of a bone screw unlocking devicecomponent of the system;

FIG. 11A shows a front view of a bone screw unlocking device componentof the system with the unlocking device component positioned and readyto be moved into an operational connection with the screw component;

FIG. 11B is a cross-sectional view along section line B-B of FIG. 11Ashowing the unlocking device component of the system, with the unlockingdevice component positioned and ready to be moved into an operationalconnection with the screw component; and

FIG. 12 shows a cross-sectional view of the lower portion of the bonescrew unlocking device component operationally engaged with the screwcomponent in an unlocked configuration.

DETAILED DESCRIPTION

Detailed embodiments are disclosed herein; however, it is understoodthat the following description is provided as being exemplary of theinvention, which may be embodied in various forms without departing fromthe scope of the claimed invention. Thus, the specific structural andfunctional details provided in the description are non-limiting, butserve merely as a basis for the invention defined by the claims providedherewith.

FIG. 1 illustrates an example of a unilateral orthopedic fixationassembly that includes a connecting rod 12 and three separate screwcomponents 3. In the example shown, the connecting rod 12 is a spinalrod having a generally circular cross section; however, it is within theconcept of the invention to secure connecting rods of any suitablecross-sectional configuration required for the need at hand.

The System

The novel spinal fixation system is generally shown at 1 in FIGS. 2A-D.FIG. 2A shows the screw component of the system 1 in an unlockedconfiguration and FIG. 2B shows the same component in a lockedconfiguration. FIG. 2C and FIG. 2D respectively show the unlockingcomponent and the locking component of the novel spinal fixation system1. The system 1 can be used to implant and lock in place a fixationassembly, such as that represented by the non-limiting example shown inFIG. 1. The system 1 includes a novel bone screw 3, which is best shownin FIGS. 1, 2A-2B, 3A-3B, 4A-4B, 8 and 12. The bone screw is a taperlock screw that can be mono-axial or multiplanar. If the screw is amono-axial taper lock screw, the longitudinal axis of the screw shaft 14coincides with the longitudinal axis of the screw 3. Preferably thescrew 3 of the system 1 is a multi-planar taper lock screw, which allowsmanipulation of the screw shaft about all three axes. The system alsoincludes a novel unlocking device or instrument component 5 and a novellocking device or instrument component 7, each of which is specificallydesigned to respectively conform to the configuration of the unlockingand locking elements of the screw 3 and to operationally interacttherewith. The screw 3 is configured and dimensioned so as to facilitateease of insertion of the screw 3 into bone and connection to surgicaldevices such as spinal rods 12 as well as facilitating easy locking andunlocking by selectively engaging the screw 3 with the other systemcomponents, the unlocking device 5 and the locking device 7,respectively. The components of the system 1 are capable of selectivelyproviding a partial lock or a full lock of the screw component 3.

The Screw Component

The screw component of the system 1 can be a mono-axial taper lock screwor a multiplanar taper lock screw. As best shown in FIGS. 1-4A-B, 8, and12, the preferred multi-planar tapered locking screw 3 includes a screwshaft 14, which defines an external helical thread 16 for penetratingbone through the application of torque. The upper portion of the screwshaft 14 terminates in a screw head 18, which is generally spherical inpart and at its uppermost surface 20 defines a screw head recess 22,which has a recess surface configuration that is complementary to theshape of a tightening and/or loosening tool. By way of example only, thescrew head recess may engage a screw driver or more specifically a hexscrew driver (not illustrated). Without departing from the concept ofthe present invention, the screw head recess 22 can also be configuredas a protrusion rather than a recess provided that the protrusion has asurface that is complementary for gripping attachment to a tool fortightening and/or loosening and provided that the height of theprotrusion above the uppermost surface 20 of the screw head 18 is notsuch that it obstructs or interferes with any of the functions of thescrew 3. In this regard, it is contemplated that a screw drivingprotrusion attached to and extending upward from the screw head may begripped by a wrench or socket driver to apply torque to drive the screwinto bone. Of course, the bone into which the screw is driven may beprepared in advance of inserting the screw in any suitable manner withinthe discretion of the surgeon such as by drilling and optionally tappinga hole to receive the screw.

As best shown in FIG. 1, the screw 3 is capable of connecting aconnecting rod 12 to multiple vertebrae, which are aligned in the spinalcolumn on different planes due to the natural curvature of the spine. Asbest shown in FIGS. 3A-3B and 4A-4B, the screw 3 component of the system1 includes a dual layered screw housing 24 that includes an outerhousing 26 and an inner housing 28. The outer housing 26 is configuredsuch that at least a portion of the inner surface 30 of the outerhousing 26 is capable of selectively sliding over a portion of the outersurface 32 of the inner housing 28 in an upward and downward directionalong the longitudinal axis of the screw 3. As best shown in FIGS. 8 and12, the locking device 7 component and the unlocking device 5 componentof the system 1 are specifically configured to quickly engage with thescrew 3 component and thus facilitate this upward locking or downwardunlocking sliding motion of the outer housing 26 relative to the innerhousing 28. The configuration of both the outer housing 26 and the innerhousing 28 are complementary, one to the other, in that when the outerhousing is slid upward in relation to the inner housing at least oneouter housing internal compression contact surface 34 is brought to bearagainst at least a portion of the outer wall 36 of the inner housing 28and by that compressive force causes the inner housing 28 in turn tomechanically transmit that compressive force inward toward the centrallongitudinal axis of the screw 3.

A screw head articulation recess 38 is defined in the interior of thelower portion 40 of the inner housing 28. The interior surface 42 of thearticulation recess 38 has a complementary surface configuration to thegenerally spherical shape of the screw head 18 so as to facilitatemulti-planar rotational articulation of the screw head 18 within therecess 38. The lower most portion of the inner housing 28 defines ascrew shaft exit portal 44, that is sized small enough to retain thespherical screw head 18 within the recess 38 but that is large enough toallow multi-directional movement of the screw shaft that extendsexterior to the inner housing 28. The recess 38 can include a recessupper edge 46 that is configured to selectively exert a lockingcompressive force against the screw head 18 when the locking device 7 isoperationally employed with the screw 3. A recess lower edge 48 can alsobe provided for the same purpose. It is also contemplated that all orportions of the interior wall of the recess 38 can selectively providethe compressive force against the screw head 18 that is sufficient tohold the screw head in a locked position.

The upper portion of the inner housing 28 defines an inner housingconnecting rod slot 50 that is sized and configured to permit aconnecting rod 12 to be placed transversely within the upper portion ofthe inner housing 28. An outer housing connecting rod slot 52 can beprovided that is in common alignment with the inner housing connectingrod slot but is not necessarily of exactly the same dimension as theinner housing slot 50. The inner housing connecting rod slot 50 candefine at least one compression contact surface 54 that when forced intocompressive contact with a connecting rod 12 present in the slot 50,serves to securely lock and hold the rod 12 in its relative position tothe inner housing 28. As discussed in greater detail below, thisrequired force is provided by the operational engagement of the lockingdevice 7 with the screw 3 that results in an upward sliding motion ofthe outer housing 26 relative to the inner housing 28. Preferably theinner housing connecting rod slot 50 is provided with an opposing uppercompression contact surface 56 and an opposing lower compression contactsurface 58, which together can selectively be forced against theconnecting rod 12 so as to secure and lock it in place within the innerhousing 28.

Preliminary to operation of the screw 3, the outer housing 26 should bepositioned in the open position; that is it should be slid downwardrelative to the inner housing 28 (see FIG. 2A). The screw shaft 14 canthen be driven into the cancellous bone by providing torsional force viaa tool configured to mate with and grip the screw head recess 22. Afterthe screw shaft 14 is positioned within the bone and the driving toolremoved from the screw 3, a connecting rod 12 can be positionedtransversely along the common course of and within the inner housingconnecting rod slot 50 and the outer housing connecting rod slot 52 (seeFIGS. 1, 3B and 4B). With the screw shaft 14 and screw head 18 beingfixed in position relative to the bone, the inner housing 28 and thecircumferentially disposed outer housing 26 can be articulated relativeto the screw head 18 as necessary to manipulate the disposition of theconnecting rod 12 within the screw 3. Upon completion of the necessarypositional adjustments of the inner housing recess 38 relative to thescrew head 18 and the adjustments of the connecting rod 12 relative tothe inner housing connecting rod slot 50, the outer housing 26 can begrasped by the operator using the complementary configured lockingdevice 7. Activation of the locking device 7 slides the outer housing 26upward circumferentially over the outer surface of the inner housing 28while the push rod 74 holds down the connecting rod 12 and the innerhousing 28 so that the screw is reconfigured from the open or unlockedposition, as shown in FIGS. 3B and 4B, to the closed or locked position,as shown in FIGS. 3A and 4A. Similarly, the operator can use thecomplementary configured unlocking device 5 to grasp the inner housing28 and slidably move the outer housing downward along the outer surfaceof the inner housing 28 from a closed or locked position, as shown inFIGS. 3A and 4A, to an open or unlocked position, as shown in FIGS. 3Band 4B. The screw 3 can be provided with an inner housing access slot 60defined through the wall of the outer housing 26, which provides accessfor the unlocking device 5 that is designed to make grasping contactwith an inner housing tool receptor 61 to facilitate quickly unlockingthe screw 3 to a mode permitting movement of the screw head 18 withinthe articulation recess 38 and removal of the connecting rod 12 from theinner housing connecting rod slot 50.

The outer housing 26 is provided with a receiving element 62 for thelocking device 7, the receiving element 62 being formed by an outwardextension of the upper portion of the outer surface of the outer housing26. Preferably, the receiving element is a proximally located annularflange 62, which is formed as a generally radial extension from theupper third portion of the outside surface of the outer housing 26. Morepreferably, the annular flange 62 radially extends from a more elevatedand therefore more operator accessible position from the upper quarterof the outer housing 26. Even more preferably, the annular flange 62 canextend from the upper fifth or less of the outer housing so long as thestructural integrity of the flange connection to the outer housingduring use is maintained. By way of example, if the outer housing has aheight of approximately 0.76 inches, the lower lip of the flange wouldbe approximately 0.40 inches from the top surface of the outer housing.This elevated position of the annular flange 62 provides a distinctadvantage to the operator by positioning the annular flange 62 above anypossible interference of anatomy contact or view obstruction when thesurgeon is attempting to access the screw and connect it to the lockingdevice 7 during the insertion and locking of the screw 3. As best shownin FIGS. 2A-2B, 3A-B, and 4A-B, the annular flange can be configured asa descending tapered lip around at least a part of the circumference ofthe upper portion of the outer housing. While the preferred annularflange 62 is proximally connected or integrally formed at the upperportion of the outer housing 26 and preferably formed within the upperthird of the vertical length of the outer housing, it is contemplatedthat the locking device and unlocking device disclosed herein may beused with a taper lock screw in which the annular flange 62 or othergripping features (such as slots or holes) on the outer housing are moredistally disposed. The receiving element 62 can include an annulargripping groove 64, which is preferably located directly beneath theannular flange 62, which is best shown in FIGS. F1, 2A-2B, 3A-B, and4A-B. The annular gripping groove 64 can serve to strengthen theoperational connection of the locking device 7 to the screw 3. Similarto the annular flange 62, the annular gripping groove 64 preferably ispresent along at least a portion of the outer surface of the outerhousing 26.

The locking device 7 and unlocking device 5 may be used to selectivelyconnect to the screw 3 and to then position the outer housing 26 alongthe surface of the inner housing 28 such that the compressive forceexerted by the outer housing 26 on the inner housing 28 is such that apartial lock position can be attained; that is, by a limited slidingmovement of the outer housing 26 relative to the inner housing 28,partial compressive pressure will be exerted on the articulation recess38 and the screw head 18 positioned therein as well on the inner housingconnecting rod slot 50 and the connecting rod 12 positioned therein. Thepartial compressive pressure of the partial lock mode allowsrepositioning of the articulating recess 38 around the screw head 18 aswell as position adjustment of the rod 12 within the inner housingconnecting rod slot 50. Using this partial lock of the screw 3, theoperator can first position the screw 3 relative to the bone into whichthe screw shaft 14 has been attached and then manipulate the innerhousing 28 relative to the screw head 18 and relative to the connectingrod 12 to optimize screw and rod position before sliding the outerhousing 26 into a fully locked position on the inner housing 28. In anexemplary embodiment, this partial locking of the screw head 18 and theconnecting rod 12 can be achieved when the outer housing 26 has beenmoved upward about 25 percent of its total possible sliding distancealong the outer surface of the inner housing 28, that is, 25 percent ofthe sliding distance from the fully unlocked to the fully lockedposition. In such an exemplary embodiment, when the outer housing 26 isslid further up along the outer surface of the inner housing 28 to aposition approximately 45 percent of the total possible slidingdistance, the screw head articulating recess 38 will be more tightlycompressed against and fully locking in relation to the screw head 18while the compression forces against the more superiorly disposedconnecting rod 12 will be such as to contain the connecting rod in thescrew 3 but still permit adjusting manipulation of the connecting rod 12within the inner housing connecting rod slot 50. In the exemplaryembodiment, further upward sliding movement of the outer housing 26 overthe surface of the inner housing 28 to a position approximately 100percent of the total possible sliding distance will apply strongercompressive forces on both the screw head 18 and the connecting rod 12so that the screw 3 will be in a fully locked position. As best shown inFIGS. 3A and 4A, when the outer housing 26 is slid upward along theouter surface 32 of the inner housing 28 such that the screw 3 is in afully locked or closed position, the uppermost extent of the outerhousing 26 and the annular flange 62 are in a general alignment with theuppermost extent of the inner housing 28. In addition, with screw 3 inthe fully locked position the top of connecting rod 12 also is generallyaligned with the uppermost extent of outer housing 26, the uppermostextent of inner housing 28 and the upper most extent of the proximalflange. As can be seen in FIGS. 3A and 4A, this provides a screw in alocked position in which there is substantially no profile above theconnecting rod. This feature advantageously reduces the structure of thescrew above the rod which might otherwise contact adjacent anatomicalstructures and cause pain or discomfort. The degree of this generalalignment of the uppermost pails of the outer housing 26 and the innerhousing 28 when the screw 3 is fully locked is demonstrated bycomparison to the position of the uppermost parts of the outer housing26 and inner housing 28 in the unlocked position, as shown in FIGS. 3Band 4B. Unlike conventional screws, the upper most part of the presentscrew 3 does not substantially extend beyond the upper level of theconnecting rod held therein and further, does not require the additionalattachment of locking set screws or nuts that in conventional systemsare attached above the level of the connecting rod.

The Locking Device Component.

To facilitate locking the novel screw 3 component of the system thelocking device 7 component is provided with specific elements which areconfigured to connect to and interact with complementary elements of thescrew 3. As best shown in FIGS. 2D, 5, 6, 7A-B and 8, the locking device7 is an elongated surgical instrument having a locking device housing 66that defines a locking device lumen 68, which extends from the lockingdevice first end 70 to the full length of device 7 exiting from thelocking device housing 66 at the locking device second end 72. As bestshown in the cross-sectional views of FIGS. 7B and 8, there is containedwithin the locking device lumen 68 a locking device push rod 74. Thelocking device push rod 74 has a push rod first end 76 and a push rodsecond end 78 and is configured and dimensioned to slidably move withinthe longitudinal axis of the elongated lumen 68 of the locking device 7.The mechanism for actuating movement of the locking device push rod 74within the lumen 68 is best seen in FIGS. 7B and 8. Movement of the pushrod 74 is initiated by a push rod activator 80, which is preferably alever action handle that is pivotally anchored adjacent the first end 70of the locking device 7 at a handle pivot point 82. The actuator handle80 is operationally connected to the push rod first end 76 via a lockingdevice connecting arm 84. The connecting arm 84 is pivotally connectedat a first pivot point 86 to a position adjacent and just distal to theproximal end 88 of the actuator handle 80. The connecting arm 84 is alsopivotally connected at a second pivot point 89, which is located at theopposite or distal end 91 of the connecting arm 84. Thus the connectingarm 84 provides an operational link for the translation of rotationallever movement of the actuator handle 80 to downward piston-likemovement of the locking device push rod within the locking device lumen68. As the handle 80 is pivotally rotated inward toward the lockingdevice housing 66, the pivotally attached connecting arm 84 is alsomoved inward, that inward movement producing a pushing force against thesecond pivot point 89 and thereby forcing the push rod 74 downwardwithin the locking device lumen 68. An opposite outward rotationalmovement of the actuator handle 80 away from the locking device housing66 pulls the connecting arm 84 upward and away from the locking devicelumen 68 and the push rod 74 contained therein. The second pivot point89 connection between the connecting rod 84 and the push rod 74translates this outward pulling motion into a longitudinal upwardmovement of the push rod 74 within the locking device lumen 68.

As best shown in FIG. 7B, the locking device push rod 74 is in contactwith a push rod biasing member 90, which is preferably a coil springdisposed around the push rod 74 between the inner wall of the lumen 68and the elongated shaft of the push rod 74. An upper retainer 92 definedby an undercut on the first end 76 of the push rod 74 and a lowerretainer 94 defined by an inwardly projecting annular ledge on the innerwall of the lumen 68 serve to define the limit of movement of the pushrod biasing member 90 as the lever action of the actuator handle 80forces the push rod 74 downward through the lumen 68 thereby compressingthe biasing member 90. The biasing member 90 provides counter force tothe lever actuator 80 and assists in releasing the locking device fromthe screw 3 after locking.

The second end of the housing 66 of the locking device 7 is best shownin FIG. 7B and FIG. 8. A compression slit 96 (sec FIG. 7A) throughopposing walls of the lower portion of the housing 66 purposely weakensthe integrity of the walls of the housing 66 that define the portion ofthe lumen 68 immediately adjacent to the slit 96 so as to allow thelumen 68 to widen or narrow as required by the passage of the push rod74 into the lower portion of the locking device lumen 68. Slits 96facilitate mounting the locking instrument onto screw 3 by permittingthe walls of the lower portion of housing 66 to spread apart to receivethe upper portion of the screw 3 within the distal end of the lockingdevice 7. The outer surface of the lower portion of the push rod 74 isprovided with push rod recesses defined at specific points to coincidewith push rod cam surfaces 100 that are defined as inward projectionsfrom the inner surface of the lower portion of the locking devicehousing 66. In operation, as the push rod 74 is forced downward throughthe locking device lumen 68, the interaction of the push rod recesses 98with the push rod cam surfaces 100 has the effect of relaxing thecompressive forces between the push rod 74 and the push rod cam surfaces100 such that the compression slit 96 is permitted to narrow accordingto the tensile nature of the material of the locking device housing 66,which is such that the housing 66, though capable of flexion, naturallyseeks to retain its shape. The locking device terminus 102 at the secondend 72 of the locking device 7 defines inwardly directed graspingprojections along at least a portion of the inner wall of the lumen 68.These grasping projections 104 are configured to fit beneath the toolreceiving element or flange 62 of the screw 3 component of the system 1and preferably at least partially seat within the annular grippinggroove 64.

FIG. 8 most clearly shows the operational relationship of the graspingprojections 104 of the locking device 7 and the flange 62 of the screw3. In operation, as the push rod 74 moves downward through the lumen 68such that the cam surfaces 100 no longer exert a compressive force onthe push rod 74, the grasping projections 104 are permitted to moveinwardly toward the center of the lumen 68 and exert a holding force onthe under side of the flange 62 of the screw 3. As the push rod 74continues downward through the lumen, the second end 78 of the push rodmakes forcible contact with a spinal rod 12 forcing it into inner andouter connecting rod slots 50, 52 of the screw 3. The second end 78 ofthe push rod 74 also makes forcible contact with the upper surface ofthe inner housing 28 so as to provide a downward force relative to theouter housing 26 of the screw 3. The opposing upward force on the flange62 of the outer housing 26 of the screw 3 created by graspingprojections 104 engaging annular flange 62 and the downward force of thepush rod 74 on the inner housing 28 of the screw 3 results in a relativeupward sliding motion of the outer housing 26 around the circumferenceof the inner housing 28. As this occurs, the resulting outer housing 26compressive forces on the inner housing 28 of the screw 3, as describedin detail earlier, serve to lock the screw head 18 of the screw 3 into afixed position relative to the articulation recess 38 of the screw innerhousing 28 and to lock the rod 12 relative to the inner housing 28. Asdiscussed earlier, a partial lock position is contemplated in whichlimited motion of the articulating head of the screw and of rod 12within the inner rod connecting rod slot 52 of the screw 3 is permitted.The partial lock position can be identified by the user by providing avisual cue or indicia on the actuator handle 80 or by providing tactileor audible feedback to the user as the actuator handle 80 moves themechanism past a cam or other frictional contact within the mechanism.The visual, tactile or audible cue or indicia indicates to the user thatthe partial lock position has been achieved. Continued application ofsqueezing force on handle 80 provides further relative upward motion ofthe outer housing 26 over the surface of the inner housing 28 to exertadditional compressive forces so as to lock the connecting rod 12 into arelative position to the screw. This fully locked position is best seenin FIGS. 2B, 3A, 4A and 8.

The Unlocking Device Component

To facilitate unlocking the novel screw 3 component of the system 1, theunlocking device 5 component is provided with specific elements whichare configured to connect to and interact with complementary elements ofthe screw 3. As best shown in FIGS. 2C and 9-12, the unlocking device 5is an elongated surgical instrument having an unlocking device housing106 that defines an unlocking device lumen 108 which extends from theunlocking device first end 110 to the full length of unlocking device 5exiting from the unlocking device housing 106 at the locking devicesecond end 112. As best shown in the cross-sectional views of FIGS. 11Band 12, there is contained within the unlocking device lumen 108 anunlocking device push rod 114. The unlocking device push rod 114 has anunlocking device push rod first end 116 and an unlocking device push rodsecond end 118 and is sized and configured to slidably move along thelongitudinal axis of the unlocking device elongated lumen 108 of theunlocking device 5. The mechanism for actuating movement of theunlocking device push rod 114 within the lumen 108 is best seen in FIGS.11B and 12. Movement of the unlocking device push rod 114 is initiatedby an unlocking device push rod activator 120, which is preferably alever action handle that is pivotally anchored to the first end 110 ofthe unlocking device 5 at a handle pivot point 122. The unlocking deviceactuator handle 120 is operationally connected to the push rod first end116 via a locking device connecting arm 124. The connecting arm 124 ispivotally connected at a first pivot point 126 to a position adjacentand just distal to the proximal end 128 of the unlocking device actuatorhandle 120. The connecting arm 124 is also pivotally connected at asecond pivot point 130, which is located at the opposite or distal end132 of the connecting arm 124. This second pivot point 130 connectiontransfers lever movement of the unlocking device actuator handle 120 tothe unlocking device push rod first end 116, where the pivotalconnection 130 forces the unlocking device push rod 114 longitudinallydownward within the unlocking device lumen 108 toward the second end 112of the unlocking device 5. An opposite movement of the actuator handle120 of the unlocking device 5 serves to pull the connecting arm 124upward and results in an upward movement of the unlocking device pushrod 114 within the lumen 108.

As best shown in FIG. 11B, the unlocking device push rod 114 is incontact with an unlocking device push rod biasing member 134, which ispreferably a coil spring disposed around the push rod 114 between theinner wall of the lumen 108 and the elongated shaft of the unlockingdevice push rod 114. An upper retainer 136 defined by an undercut on thefirst end 116 of the unlocking device push rod 114 and a lower retainer138 defined by an inwardly projecting annular ledge on the inner wall ofthe unlocking device lumen 108 serve to define the limit of movement ofthe unlocking device push rod biasing member 134 as the lever action ofthe unlocking device actuator handle 120 forces the push rod 114downward through the lumen 108 thereby compressing the unlocking devicepush rod biasing member 134.

As best shown in FIG. 11B and FIG. 12, an outer sleeve 140 is providedin a slidable circumferential disposition around at least a portion ofthe lower part of the unlocking device 5, adjacent to the second end112. As best shown in FIGS. 9, 10 and 11B, this outer sleeve 140 is, atits bottom edge, provided with a connecting rod slot 142, which is sizedand configured to permit easy through passage of a spinal connecting rod12. The unlocking device outer sleeve 140 is connected to the unlockingdevice push rod 114 by an outer sleeve connecting pin, which provides acoordinated movement connection of the push rod 114 and the outer sleeve140 through a connecting pin slot 142 defined through the wall of thelower portion of the unlocking device housing 106. Thus, in operation, acompressive movement of the unlocking device actuator handle 120 throughthe pivotal connection to the connecting arm 124 causes a downwardmovement of the unlocking device push rod 114 through the lumen 108 andthat same downward movement is communicated to the outer sleeve 140 bythe mechanical connection of the push rod 114 via the connecting pin144. Similarly, an outward movement of the actuator handle 120 willresult in a coordinated longitudinal upward movement of the unlockingdevice push rod 114 and its connected outer sleeve 140.

As best shown in FIGS. 11B and 12, the outer surface of the lowerportion of the unlocking device push rod 114 is provided with unlockingdevice push rod recesses 146 defined at specific points to coincide withunlocking device push rod cam surfaces 148 that are defined as inwardprojections from the inner surface of the lower portion of the unlockingdevice housing 106.

The second end of the unlocking device housing 106 terminates in atleast a pair of opposing screw grasping elements 150 that are sized andconfigured to easily pass through the inner housing access slots 60 thatare defined in the outer housing 26 of the screw 3. Passage of thegrasping elements 150 through the inner housing access slots 60 permitsthe grasping elements 150 to make an operational connection with theinner housing tool receptor 61. As best shown in FIGS. 11B and 12, theconfiguration of the grasping elements 150 and the complimentary innerhousing tool receptor 61 facilitates the holding and the upward pullingof the inner housing 28 of the screw while the outer sleeve 140 of theunlocking device 5 is pressed against the top of the outer housing 26when the operator actuates the handle 120 of the unlocking device so asto unlock the screw 3. This relative motion of the outer housing 26 andthe inner housing 28 of the screw 3, as described earlier has the effectof either partially unlocking the screw or fully unlocking the screw 3as desired depending upon whether the handle 120 is partially or fullysqueezed.

In operation, when the operator of the unlocking device 5 selectivelymoves the unlocking device actuator handle 120 so as to push theunlocking device push rod 114 downward through the unlocking devicelumen 108, the surfaces defining the unlocking device push rod recesses146 interact with the unlocking device push rod cam surfaces 148 definedby the unlocking device housing 106 to move the grasping elements 150into a holding connection with the inner housing tool receptor 61. Thismotion of the unlocking device push rod 114 at the same time serves tomove the connected outer sleeve 140 downward against the outer housing26 of the screw 3. This pushing downward on the outer housing 26 of thescrew 3 while pulling upward on the inner housing 28 of the screw 3,serves to partially or fully unlock the screw 3.

FIG. 12 most clearly shows the operational relationship of the graspingelements 150 of the unlocking device 5 and the inner housing toolreceptor 61 of screw 3. As discussed earlier in detail, a partial lockor partial unlock position can be permitted which allows limited motionof the rod 12 within the inner rod connecting rod slot 52 of the screw3. As with the locking device 7 of the system 1, the unlocking device 5can be provided with a way of identifying when the unlocking device 5 isin a partial unlocked position by providing a visual cue on theunlocking device actuator handle 120 or by providing tactile feedback tothe user as the actuator handle 120 moves the mechanism past a cam orother frictional contact within the mechanism. Further relative upwardmotion of the inner housing 28 within the outer housing 26 relievesadditional compressive forces so as to unlock the connecting rod 12 intoa relative position to the screw. This fully unlocked position is bestseen in FIGS. 1, 2A, 3B, 4B and 12.

The materials used to construct the present invention are those whichhave sufficient strength, resiliency, and biocompatibility as is wellknown in the art for such devices. Methods of manufacture of suchsurgical implant devices are also well known in the art. By way ofexample only, suitable materials for screw 3 include titanium, titaniumalloys including Nitinol, stainless steel, and cobalt chrome alloys. Thelocking and unlocking instruments are intended to be cleaned,re-sterilized and used in multiple procedures, and so may be made ofstainless steel or other suitable materials for this purpose. Becausethe locking and unlocking instruments are not intended to be implantedin the body, implant grade materials are not required and the additionalexpense for such materials may not be justified; however, such materialsmay be used if desired.

In use, a surgeon accesses the patient's spine in a known manner eitherusing open surgical techniques or minimally invasive techniques, andprepares the bone to receive screws, as is deemed appropriate under thecircumstances. Multiple taper lock screws are inserted into boneaccording to the operative plan of the surgeon, and a rod is placed inor adjacent the inner housing recess and extends through slots 50, 52 toadjacent screws. The surgeon then uses the locking instrument to lock orpartially lock each screw to the rod. Advantageously, the surgeon maypartially lock each screw and before finishing the locking step mayreadjust the arrangement of the screws and rods to better suit thesurgical situation. It has been found that partially locking the screwsand then readjusting the positioning of the rod and screws may permitthe surgeon to obtain superior surgical results. That is, with priorscrews and rods, if the surgeon attempted to partially lock the screws,i.e., partially tighten the screw or nut, and then to readjust theconstruct, the construct under the forces exerted by the anatomy wouldnot remain in position to allow the surgeon to return and tighten thescrews to lock the screws. With the taper lock screws and the lockerdisclosed herein, the surgeon may partially lock the screws so that ashe or she subsequently adjusts the screws and rods the construct willstay in the adjusted position. The partial locked position of the screwprovides great flexibility to the surgeon in making any adjustmentsdeemed necessary such as, but not limited to, compression, distraction,and rotation of the entire construct or of individual bodies associatedwith the screws. After completing whatever adjustments are required, thesurgeon can then fully lock each screw with the locking instrument. Thistechnique is particularly advantageous for deformity cases, where longconstructs need to be adjusted during surgery in order to obtain thebest clinical results. As mentioned after final positioning, with theplurality of screws in the partial lock position, the surgeon uses thelocking instrument to fully lock each screw and rod together in anyorder chosen by the surgeon. The convenient engagement features on thescrew and locking tool enable the surgeon to quickly mount the lockinginstrument to each screw and fully lock each screw in rapid sequence. Incontrast, conventional systems require the surgeon to apply apredetermined amount of torque to each screw, which is time consumingand more tedious than the present quick lock system. Should the surgeonfully lock the screw and thereafter need to adjust the screw, theunlocking instrument may be used to partially or fully unlock the screwto permit adjustment. In the event of revision surgery, the unlockinginstrument may be used to partially or fully unlock the screw, and thesurgeon may then adjust or revise the construct as necessary. It shouldbe noted that in the event of revision surgery, the provision of theproximal flange on the outer housing to engage the locking instrumentcan be particularly advantageous. Not only does the proximal flangefacilitate better visibility and access during initial implantation byengaging the locking and unlocking instruments in a proximal locationaway from the bone bed, during revision surgery the proximal location ofthe features of the inner and outer housing for engaging the locking andunlocking instruments facilitates accessing those features more readilyduring revision surgery. That is the surgeon need not remove tissuearound the screw all the way to bone at the bottom of the screw in orderto attempt to mount the locking and more particularly the unlockinginstrument over the screw.

It is contemplated to provide the system 1, including the multi-planartaper lock screw 3, the locking device 7 and the unlocking device 5 aspart of a kit for use in a surgical process, the kit comprising at leasttwo of the screws 3 and at least some of the associated tools for usingthe screws to connect a surgical rod to adjacent bones or bonefragments. In addition, the kit can contain surgical rods, such as, forexample, spinal rods. Additional devices such as cross-connectors, hooksor links can also be included in the kit.

Each of the embodiments described above are provided for illustrativepurposes only and it is within the concept of the present invention toinclude modifications and varying configurations without departing fromthe scope of the invention that is limited only by the claims includedherewith.

What is claimed is:
 1. A taper lock screw comprising: a screw includinga shaft and a superiorly positioned screw head; an inner housingincluding an uppermost portion; an outer housing including an uppermostportion, the outer housing circumferentially disposed around at least aportion of the inner housing and slidably movable relative to the innerhousing to secure a connecting rod within the inner housing; and anannular flange projecting outwardly from the uppermost portion of theouter housing, the annular flange having an uppermost portion, whereinthe inner and outer housings are slidably translatable relative to oneanother to cause transitioning of the taper lock screw between a lockedposition and an unlocked position, wherein the uppermost portions of theconnecting rod and the flange are substantially coplanar when the taperlock screw is in the locked position.
 2. The taper lock screw of claim1, wherein the flange is positioned to overhang a circumferentiallydefined annular gripping groove that is configured to facilitategrasping contact of a grasping tool for facilitating locking of thetaper lock screw.
 3. The taper lock screw of claim 1, wherein the flangeis positioned to overhang an annular gripping groove circumferentiallydefined in an outer surface of at least a portion of the outer housing.4. The taper lock screw of claim 1, wherein an articulation recess isdefined in a lower portion of the inner housing, and wherein thearticulation recess is dimensioned and configured to retain the screwhead of the screw within the inner housing while allowing the screw headto rotate within the articulation recess.
 5. The taper lock screw ofclaim 4, wherein the articulation recess includes at least one contactsurface positioned against the screw head.
 6. The taper lock screw ofclaim 1, wherein the outer housing is slidable relative to the innerhousing to contact the inner housing with sufficient compressive forceto contact and secure the connecting rod within the inner housing. 7.The taper lock screw of claim 1, wherein the outer housing ispositionable relative to the inner housing to compress the outer housingagainst the inner housing to transition the taper lock screw to apartially locked position sufficiently locking the taper lock screwwhile permitting movement of the connecting rod within the innerhousing.
 8. The taper lock screw of claim 1, wherein the uppermostportion of the flange and the uppermost portion of the connecting rodare substantially coplanar with the uppermost portion of the innerhousing when the taper lock screw is in the locked position.
 9. Thetaper lock screw of claim 1, wherein the uppermost portion of the flangeand the uppermost portion of the connecting rod are substantiallycoplanar with the uppermost portion of the outer housing when the taperlock screw is in the locked position.